Automatic exposure control device for a photographic camera

ABSTRACT

An automatic exposure control device for a photographic camera provided with an exposure control circuit including a light receiving element receiving the scene light passing through an objective lens and a diaphragm, and operating in accordance with photographic conditions such as the generated current of said light receiving element, the set shutter speed and the set film sensitivity in the camera, an electromagnetic coil whose magnetic field varies according to the output of said exposure controlling circuit, and a retaining member retaining the diaphragm in a fully open state so biased that the aperture will be reduced from its fully open condition. While closing the switch of the exposure controlling circuit prior to the shutter is initiated for actuating the exposure controlling circuit, releasing the retaining member thereby causes the diaphragm to start reducing the aperture size and when the brightness of the scene light passing through said objective lens and the diaphragm becomes the correct value with respect to the set shutter speed and the set film sensitivity, the diaphragm aperture is prevented from being reduced according to the variation of the magnetic field of said electromagnetic coil for controlling the diaphragm aperture.

United States tent n 1 Kuramoto et al.

[ Dec. 11, 1973 AUTOMATIC EXPOSURE CONTROL DEVICE FOR A PHOTOGRAPHICCAMERA [75] Inventors: Yoshio Kuramoto; Kayoshi Tjujimoto, both ofOsaka; Hiroshi Ueda, Nara, all of Japan [73] Assignee Minolta CameraKabushilri Kaisha,

Osaki-shi, Osaku-fu, Japan 22 Filed: May 18,1972

21 Appl.No.:254,506

[30] Foreign Application Priority Data May 31, 1971 Japan 46/37049 [52]US. Cl 95/10 CD, 95/64 D [51] Int. Cl....., G03b 7/08, G03b 9/06 [58]Field of Search 95/10 CE, 10 CD, 95/64 R, 64 D [56] References CitedUNITED STATES PATENTS 3,528,351 9/1970 Konig 95/10 CD 3,605,588 9/l971Ort et al... 95/10 CD 3,6l 1,895 10/1971 Albe'dyll 95/10 CD PrimaryExaminerSamuel S. Matthews Assistant ExaminerRussell E. Adams, Jr.Attorney-Watson et al.

[5 7] ABSTRACT An automatic exposure control device for a photographiccamera provided with an exposure control circuit including a lightreceiving element receiving the scene light passing through an objectivelens and a di aphragm, and operating in accordance with photographicconditions such as the generated current of said light receivingelement, the set shutter speed and the set film sensitivity in thecamera, an electromagnetic coil whose magnetic field varies according tothe output of said exposure controlling circuit, and a retaining memberretaining the diaphragm in a fully open state so biased that theaperture will be reduced from its fully open condition. While closingthe switch of the exposure controlling circuit prior to the shutter isinitiated for actuating the exposure controlling circuit, releasing theretaining member thereby causes the diaphragm to start reducing theaperture size and when the brightness of the scene light passing throughsaid objective lens and the diaphragm becomes the correct value withrespect to the set shutter speed and the set film sensitivity, thediaphragm aperture is prevented from being reduced according to thevariation of the magnetic field of said electromagnetic coil forcontrolling the diaphragm aperture.

9 Claims, 6 Drawing Figures tartar" m 1 m 01 t 1 AUTOMATIC EXPOSURECONTROL DEVICE FOR A PHOTOGRAPHIC CAMERA BACKGROUND OF THE INVENTION Thepresent invention relates to an automatic exposure control device for aphotographic camera in which the shutter speed is set up beforehand andthe diaphragm aperture is controlled in response to the intensity of thelight brought incident upon a light receiving element passing throughthe objective lens and the diaphragm from the object to be photographed.

In prior photographic cameras in which exposure is controlled by thegenerated current of a light receiving element receiving the scene lightpassing through the objective lens and the diaphragm, the lightreceiving element must be arranged so that the formation of images onfilms are not arrested by the scene light. Accordingly, the lightreceiving element, in a single lens reflex camera, is normally arrangedin the reflected optical path where, by means of a moving reflectingmirror, the scene light is reflected in a view finder.

However, such a reflected optical path, in photography, cannot controlexposure when film exposure is made for the reason that the scene lightwhich had passed through the objective lens and the diaphragm is cut offby the moving reflecting mirror.

Hence, the scene light must be detected prior to exposure so as to bememorized, and a memory means controlling exposure in accordance withthe memory value becomes necessary. In addition, when the scene lightprior to exposure is detected in a condition in which the diaphragm isfully opened, it becomes necessary to provide a means by which the valuedetected may be converted to the diaphragm aperture in photographing.

Therefore, it has been quite difficult to receive the light that passedthrough the objective lenses and the diaphragm apertures with the use ofthe prior art devices wherein the generated current is detected toautomatically control the diaphragm aperture forming the correctexposure with respect to shutter speed set up in a camera and the filmsensitivity of the film used in it.

THE OBJECTS OF THE INVENTION One object of the present invention is toprovide an automatic exposure control device for a photographic camerain which, by detecting the generated current of a light receivingelement receiving the scene light which passed through an objective lensand a diaphragm, an exposure controlling circuit automatically controlsthe correct diaphragm aperture to control the exposure, with respect toshutter speed set up in the camera and the film sensitivity of the filmused in it.

Another object of the present invention is to provide an automaticexposure control device for a photographic camera in which, when anattachable lens provided with an objective lens having various aperturesand focal lengths and a diaphragm is attached to a camera, an exposurecontrolling circuit, detecting the generated current of a lightreceiving element receiving the scene light passing through theattachable lens and the diaphragm, controls the diaphragm aperture ofthe attachable lens in order to decide the correct value with respect tothe shutter speed set up in the camera and the film sensitivity of thefilm used in it.

Still another object of the present invention is to provide an automaticexposure control device for a photographic camera which, while closingthe switch of an exposure controlling circuit thereby operating theexposure controlling circuit and consequently, by releasing theretention of the retaining member which retains a diaphragm so biased ina fully open condition that the diaphragm aperture will be decreasedfrom its fully open condition, and reducing the diaphragm aperture size,the intensity of the scene light passing through the objective lens andthe diaphragm, while said aperture size is reduced, becomes the correctvalue with respect to the shutter speed set up in the camera and thefilm sensitivity of the film used in it, and checks the reduction of thediaphragm aperture size and thereby controls exposure.

Other and further objects of the present invention are to provide anautomatic exposure control device for a photographic camera in which, bydetecting the generated current of a light receiving element receivingthe scene light that passed through an objective lens and a diaphragm,an exposure controlling circuit retains said diaphragm so that theaperture size will be reduced by actuating the retaining member from itsfully open position so as to decide a correct value with respect to theshutter speed set up in the camera and the film sensitivity of the filmused in it. Also, while the diaphragm is being retained by the retainingmember, the light receiving element is withdrawn from the optical pathwhere images are formed on films passing through said objective lens,after which the shutter is caused to operate.-

SUMMARY OF THE INVENTION The present invention, for the accomplishmentof the aforementioned objects, relates to an automatic exposure controldevice for a photographic camera provided with an exposure controlcircuit including a light receiving element receiving the scene lightpassing through an objective lens and a diaphragm, and operating inaccordance with photographic conditions such as the generated current ofthe light receiving element, the shutter speed set up in the camera andthe film sensitivity of the film used in it. Also included is anelectromagnetic coil whose magnetic field varies according to the outputof the exposure controlling circuit, and a retaining member retainingthe diaphragm in a fully open condition and so biased that the aperturewill be reduced from the fully open condition. While closing the switchof the exposure controlling circuit prior to the time the shutter iscaused to initiate, the exposure controlling circuit is actuated and theretention of the retaining member is released at a fully open apertureposition thereby causing the diaphragm to begin reducing the aperturesize. And when the brightness of the scene light passing through theobjective lens and the diaphragm approaches the correct value withrespect to the shutter speed set up in the camera, and the filmsensitivity of the film used in it, the diaphragm aperture size isprevented from being reduced according to the variation of the magneticfield of the electromagnetic coil thereby controlling the diaphragm.

At the same time that an exposure controlling circuit is caused to startoperating prior to the initiating of the shutter, while reducing thediaphragm aperture size from its fully open position, detects the scenelight passing through the diaphragm and an objective lens and, when itsdetection value approaches the correct value with respect to the shutterspeed and the film sensitivity set up in the camera, the aperture isprevented from being reduced by means of the diaphragm, therebycontrolling the diaphragm aperture automatically.

Therefore, according to the present invention, the

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational side-viewshowing the arrangement of the optical system and the light receivingelement in the first embodiment of the present invention.

FIG. 2 is a perspective view showing the arrangement of the principalparts of the first embodiment.

FIG. 3 is a circuit diagram showing an exposure controlling circuit inthe first embodiment.

FIG. 4 is a perspective view showing the arrangement of the principalparts of a second embodiment in accordance with the present invention.

FIG. 5 is a circuit diagram showing the exposure controlling circuit ofthe second embodiment.

FIG. 6 is a perspective view showing the arrangement of the principalparts of a third embodiment in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the arrangement ofthe optical lens system and the light receiving element of the camera inaccordance with a first embodiment of the present invention. Objectivelens 1 is provided with a diaphragm 2. These are structurally arrangedas being an attachable lens type, although they are fitted firmly intothe camera. The structure of the present device is of the attachablelens type in each of the embodiments of the invention.

A reflecting mirror 3 is supported for rotation on an axle about itsaxiswithin the camera body. This reflecting mirror 3 may be moved, inrelation to the operation of the shutter release, to its position ofrest thereby cutting off the scene light which passed through objectivelens 1 and diaphragm 2 so that the scene light will not reach the film(not shown in the drawing). Mirror 3 serves to reflect the scene lighton a focusing plate 4 of the camera, and permits entry of the scenelight to an eye-piece lens 7 via a condenser lens 5 and a pentagonalprism 6, the mirror may also be moved to a position where it iswithdrawn from the scene light by which exposure is given to the film.

A small reflecting mirror 5', disposed firmly at an angle of 45 to theoptical axis, is provided at the center of condenser lens 5. Also, alight receiving element 8 is located on the optical axis reflected bythe mirror 5. Such a light receiving element may comprise aphotoelectric cell which is highly responsive to the incident light.

In FIG. 2, a first pin 9a and a second pin 9b are mounted on a releasebutton 9 arranged for movement up and down with respect to the camerabody. An insulated plate 8,, is provided on a source switch S, which isbiased to close the exposure controlling circuit, to be hereinafterdescribed. As button 9 is moved downwardly, pin moves slightly away fromplate 8, at an early stage of the downward stroke thereby closing switch8,. Therefore, an electromagnet 15 is excited by the exposurecontrolling circuit, to be hereinafter described.

Moreover, when release button 9 is pressed down, the second pin 9brotates a lever 10 clockwise about an axle on the camera body extendingthrough axle hole 10b. Lever 10 is biased for counterclockwise rotationabout the axle through hole 1012, by means of a spring 1 1. A slideableworking plate 12 engages with the lower end 10a of lever 10.

This working plate 12 is provided with a flange 12c which is engageablewith a diaphragm adjusting pin 16 arranged on one side of the attachablelens and is further provided with a pin 12b engageable with an arm 13bof a stop lever 13 to be hereinafter described. Plate 12 also has atoothed portion 12a thereon engageable with a pawl 13e of stop lever 13.

Stop lever 13 is supported for rotation about an axle on the camera bodyextending through a hole 13d and consists of a three armed lever biasedfor rotation in a clockwise direction by means of a spring 14. Pawl l3eis formed at one end of arm 13a facing forwardly in the direction ofclockwise movement of the lever. The side of arm 13a, opposite the sideat which pawl l3e is formed, faces the electromagnet 15 which is mountedfirmly within the camera body. Lever 13 is therefore attracted by theelectromagnet 15 whose magnetic field varies according to the output ofthe exposure controlling circuit as to be hereinafter described morefully. Also, the edge of the second arm 13b, which faces forward in thedirection of rotation of lever 13, engages pin 12b of working plate 12,as shown in FIG. 2. Moreover, the edge of third arm 13c, which facesforward in the direction of rotation of lever 13, engages a pin 21b of aretaining lever 21 which, as can be seen, engages with lever 10.

Retaining lever 21 is supported for rotation about an axle mounted onthe camera body and extending through an axle hole 210. Lever 21 isbiased for clockwise rotation by means of a spring 22, and is providedwith a U-shaped arm 21a at one end thereof. An arm of lever 10 isengageable with or detachable from the U-shaped end 21a in accordancewith the rotational position of lever 10. That is, the U-shaped end 210comes into contact with lever 10 when release button 9 is moved up andlever 10 is rotated counterclockwise; and end 21a is out of contact withlever 10 and retains the arm of lever 10 therewithin when release button9 is pressed down and lever 10 is rotated clockwise.

Also, one arm 23a of a camera release lever 23 is disposed directlybelow the lower end 90 of release button 9 and the other arm 23c isengageable with and detachable from an arm 24b of an intermediate lever24. This intermediate lever 24 is supported for rotation about an axlemounted on the camera body and extending through a hole 24a. Also, lever24 is biased for rotation in the direction of the arrow A by means of aspring, not shown in the drawing. The other arm 24c of lever 24 isengageable with and detachable from an arm 25a of a mirror lever 25which is supported for rotation about axle 25b in the direction of thearrow B. Mirror 3 of the camera is fixedly mounted on rotatable axle 25bof mirror lever 25.

A mirror return lever 27 is also supported on axle 25b for rotation inthe direction of the arrow C by means of a spring (not shown) which hasa stronger spring characteristic as compared to the spring used to biaslever 25 in the direction of the arrow B. A pin 27a is mounted on mirrorreturn lever 27 and, when mirror lever 25 is rotated in thecounterclockwise direction B, pin 27a engages with a side edge 250 ofthe mirror lever, thereby retaining mirror 3 in a parallel position withrespect to the optical axis of the objective lens. Also, when mirrorreturn lever 27 is rotated clockwise, pin 27a tends to return mirror 3from the above position to the rest position located at an angle of 45degrees to the optical axis.

Moreover, a projection 27b is formed on mirror return lever 27 and isengageable and detachable from a hook 26b of a three-armed connectinglever 26.

This three-armed connecting lever 26 is supported for rotation about anaxle mounted on the camera body and extending through an axle hole 26a.Lever 26 is biased for rotation in a clockwise direction and is providedwith a pin 26c mounted at the end of its second arm. The third arm 26dof lever 26 is located above a gear 28. This gear 28 meshes with a gear47 of the rear curtain of the shutter as shown in FIGS. 4 and 6, to behereinafter described, and is mounted for rotation about an axleextending through an axle hole 28a. Also, gear 28 is provided with aprojecting pin 28b. This pin 28b is engageable with third arm 26d duringcompletion of the driving of the rear curtain of the shutter and so asto rotate connecting lever 26 clockwise. Thus, lever 21 is rotatedcounterclockwise against spring 22 and lever 13 is rotatedcounterclockwise against spring 14 via pin 21b. Pin 26c of connectinglever 26 therefore releases the engagement between pawl 13c and toothedportion 12a of working plate 12 during counterclockwise rotation of stoplever 13 thereby moving it into contact with electromagnet 15. Also,hook 26b is detached from projection 27b of mirror return lever 27 tothereby release the turning retention of lever 27.

Diaphragm adjusting pin 16 is mounted firmly into a rotatable diaphragmworking ring 17 so arranged that the optical axis of objective lens 1 isat the center within the attachable lens. This diaphragm working ring 17is biased for rotation in a clockwise direction by means of a spring(not shown in the drawing) and a projecting pin 17a is provided on ring17 for engagement with a projection 18a of a diaphragm ring 18 which isrotatable about a common center with the diaphragm working ring 17.

This diaphragm ring 18 is biased for rotation in a clockwise directionby means of a relatively weak spring (not shown) so that pin 17a will bemaintained in engagement with projection 18a for controlling the openingand closing of diaphragm blades 19 (only one of which is shown in thedrawing). That is, when diaphragm ring 18 rotates counterclockwise,diaphragm blades 19 are opened, and when the diaphragm ring rotatesclockwise, the blades are closed.

The exposure controlling circuit is illustrated in FlG. 3. In thedrawing, E represents a power battery and S shows a switch which isclosed at an early stage of the stroke of shutter button 9 when it ispressed down.

When switch H is closed, the current generated by the scene lightpassing through objective lens 1 and diaphragm 2 and supplied forphotoelectric cell 8 is amplified by a transistor Tr Transistor Tr Trand Tr, are connected to cause a short circuit between the terminals ofphotovoltaic cell 80, to remove the leakage current of this cell and tomake it possible to detect precisely generated current within the limitsof low intensity if illumination.

Transistors Tr and Tr constitute a differential amplifier circuit whichmay utilize high input transistors or may be amplified by transistorswith two or three stages, so that the current flowing through transistorTr may be ignored, by decreasing the base currents of transistors Tr andTr Transistor Tr diode D and resistance R are designed to improve theproperties of the differential amplifier circuit. Variable resistance R,isdesigned to set up the shutter speed and the film sensitivity in thecamera.

With the arrangement of such a circuit as described above, theshort-circuit current of photovoltaic cell is amplified by transistor Trand the collector current of transistor Tr, varies in a manner dependingupon an exponential function in proportion to the quantity of lightbrought incident upon photovoltaic cell 80. However, the voltagecompressed logarithmically by diode D and transistor Tr having theproperties of a diode, is impressed between the collector of transistorTr and the base of transistor Tr Hence, the quantity of light broughtincident upon photovoltaic cell 80 varies according to the brightness ofan object and the regulated aperture of the diaphragm of an attachablelens, the voltage varied into a linear form according to the brightnessof an object and the regulated aperture of the diaphragm of anattachable lens being impressed on the base of transistor Tr which isone of the components of the differential amplifier circuit.

On the base of transistor Tr which is another of the components of thedifferential amplifier circuit, the voltage is impressed by slider 280in a linear form according to the shutter speed and the film sensitivitythat are set up in the camera.

Accordingly, when switch S is closed by shutter release button 9 andelectromagnet 15 is excited, the aperture is cut down by the diaphragmblade from a state in which the aperture is fully opened, and,thereafter, when the base potential of transistor Tr according to thebrightness of an object and the aperture of the diaphragm of anattachable lens and the base potential of transistor Tr coincide witheach other, electromagnet 15 is demagnetized so that the aperture sizewill not be reduced further by means of the diaphragm blade.

Referring to FlG. 2 showing the structural arrangement of the invention,a condition in which the shutter has been charged is shown therein withworking plate 12 having been moved completely to the right and thediaphragm blade having been fully opened.

When shutter release button 9 is pressed down in such a position asdescribed above, switch S is closed, the exposure controlling circuit iscompleted, the excited electromagnet 15 is attracted to the armature ofstop lever 13, and pawl 13c of lever 13 is maintained in a positionwhere it is withdrawn from toothed portion 12a of working plate 12.

Also, during downward movement of button 9, pin 9b rotates lever 10clockwise, working plate 12 is caused to start sliding to the left andthe aperture size is reduced gradually as the diaphragm blades begin toclose 7 from their'fully open position via flap 12c, diaphragm adjustingpin 16, diaphragm working ring 17 and diaphragm ring 18. When leverengages with the U- shaped end of retaining lever 21, the latter rotatesclockwise to retain lever 10, and pin 21b is moved away from the thirdarm 13c of stop lever 13.

When, as a result of the action performed by the exposure controllingcircuit as described hereinabove, the diaphragm aperture is adjustedcorrectly to the brightness of an object and the shutter speed and thefilm sensitivity set up in the camera. Also, electromagnet isdemagnetized, stop lever 13 rotates clockwise by means of spring14, pawl13c engages with toothed portion 12a of working plate 12, and thereduction of the aperture size by diaphragm blades isstopped as plate 12is moved to the left.

Thereafter, when shutter release button 9 is pressed down until itslower end 90 contacts camera release lever 23, such lever 23 is rotatedclockwise thereby allowing intermediate lever 24 to turn in thedirection shown by arrow A. Hence, arm 25a of mirror lever 25 isdisengaged from arm 250, mirror lever 25 turns in the direction shown byarrow B, and mirror 3 is rotated to a position at which an object isphotographed. Upon completion of the above rotation, the shutter isreleased in a known manner. When the driving of the rear curtain of thefocal plane shutter is completed, pin 28b of gear 28 engages with thirdarm 26d of connecting lever 26 to rotate it clockwise so that its hookportion 26b will be disengaged from projection 27b of mirror returnlever 27 for turning the latter in the direction shown by the arrow C.Pin 27a therefore rotates mirror lever 25 clockwise to return it to itsoriginal position, and pin 26c of connecting lever 26 rotates retaininglever 21 counterclockwise so that the U-shaped end 21a thereof releaseslever 10. Also, pin 21b of retaining lever 21 rotates stop lever 13counter-clockwise to bring its armature into contact with electromagnet15, thereby withdrawing pawl 13e from toothed portion 12a of workingplate 12.

On the other hand, now that lever 10 has been released by retaininglever 21 it is rotated counter-clockwise by means of spring 11, and thelower end 10a thereof moves engagement plate 12 to the right as in FIG.2. Flap 12c of plate 12 rotates diaphragm working ring 17counterclockwise via diaphragm adjusting pin 16 of the attachable lens,and pin 17a engages with projection 18a of diaphragm ring 18 to rotatecounterclockwise together for opening diaphragm blade 19 fully. Pin 17ais then returned to its original position.

A diaphragm aperture setting ring 20 is shown for adjusting the aperturemanually to take photographs when it is desired to set the diaphragmaperture beforehand by manual operation.

FIG. 4 illustrates a mechanical arrangement of the second embodiment fora camera of the attachable lens type relating to the present invention,and FIG. 5 illustrates the electrical control circuit for thisembodiment. In this embodiment the same reference numerals are used forthose parts of similar construction and function as the firstembodiment.

Release member 9 is shown interconnected with a release button 29 via acoupling plate 30 which is firmly mounted to the upper end of member 9so that the member 9 and button 29 may function as a unit.

When shutter button 29 is pressed down in the direction shown by thearrow F, coupling plate 30 is also pressed down, thereby moving downrelease member 9 so that at an early stage of the downward stroke, thefirst pin 9a moves away from insulating piece 8, of switch S for closingthe exposure controlling circuit. When release member 9 is furtherpressed down, its lower end 9c engages with one end 31b of a lever 31which is supported for rotation about an axle mounted on the camera bodyand extending through axle hole 31a. Lever 31 is biased for clockwiserotation by means of a spring (not shown). Hence working lever 32, whichbears against the other end 310 of lever 31 and which is biased in thedirection shown by the arrow D by means of a spring (not shown in thedrawing), starts to rotate clockwise about an axle extending throughaxle hole 32b when working lever 32 is out of engagement with end 310.Since a flap 32a of working lever 32 engages with diaphragm adjustingpin 16 of the attachable lens, the diaphragm blade of the same structureas in the first embodiment starts to regulate the aperture thereof. Andthe diaphragm aperture information fit for the brightness of an objectis supplied to light receiving element 8 having good responsitivity tothe brightness of the light received in the same manner as in the firstembodiment.

A stop lever 33 is biased to rotate clockwise about an axle extendingthrough hole 330 by means of a spring (not shown in the drawing), 50that the armature formed on one arm 33a having a pawl 33d is attractedto a permanent magnet 44 against the turning tendency of stop lever 33.An electromagnetic coil 45 is wound about permanent magnet 44 as shownin both FIGS. 4 and 5. When the output generated by the shutter speedand the film sensitivity which are set up in the camera, and the outputgenerated in light receiving element 8 -by the scene light broughtincident upon light receiving element 8 via the objective lens and thediaphragm, are put in a state of balance, permanent magnet 44 and themagnetic force of inverse polarity are formed on electromagnetic coil45, no attraction is exerted by the permanent magnet 44. Stop lever 33therefore rotates clockwise, and pawl 33d engages with toothed portion32a formed on working lever 32 to restrain the rotation of working lever32. At the same time, the other arm 33b of stop lever 33 is out ofengagement with arm 34b of mirror lever 34 so that mirror lever 34rotates in the direction shown by the arrow B about its axle 34extending through opening 34a thereby rotating moving mirror 3 in thesame direction via axle 35. At the same time, the other arm 34c ofmirror lever 34 rotates shutter release lever 37 clockwise, and therebyfront curtain retaining lever 38 is actuated to rotate counterclockwise.Therefore, retaining pawl 38a of front retaining lever 38 releases theretention of cam 39 which is mounted on axle 40. A front curtain gear41, firmly mounted on axle 40 causes a front curtain 46 to be driven viaa gear 42 by means of a front curtain axle 43 biased for rotation in thedirection of the arrow G.

On the other hand, a rear curtain gear 47 is fitted freely into axle 40so that after it has been retained by the time interval of the shutterspeed which is set up by means of the shutter mechanism (not shown), itis released for causing a rear curtain 51) to be driven via a gear 48which is biased for rotation in the direction of arrow H. g

A connecting lever 56, as in the first embodiment, is mounted forcounterclockwise rotation so that at the instant the exposure isterminated, it releases the retention of mirror return lever 36.Therefore, lever 36 rotates in the direction shown by arrow C by meansof a spring (not shown in the drawing), and its pin 36a engages withside edge 34d of mirror lever 34 to rotate mirror lever 34 in the samedirection, thereby returning mirror 3 to its original position.

Spring 57 is coupled between connecting lever 56 and a lever 58 whichsupported for rotation about the same axle as that of lever 56. Lever 58rotates counterclockwise in accordance with the counterclockwiserotation of coupling lever 56 for turning stop lever 33 in the samedirection as a result of which its pawl 33d is out of engagement withtoothed portion 32a and its armature is brought into contact withpermanent magnet 44.

While the winding of a film may be done, as is generally known, whenwinding lever 51 rotates counterclockwise after photographing iscompleted front curtain gear 41 rotates clockwise via gears 52, 53, 54and 55, and the shutter is locked since cam 39 is mounted on gear 41 andengages with retaining pawl 38a of front curtain retaining lever 38.

Referring to the difference between the circuit of the first embodimentillustrated in FIG. 3 and the circuit of FIG. 5, with respect to theconnection of electromagnet coil 45, the former is connected with thecollector of transistor Tr whereas the latter is connected with thecollector of transistor Tr Hence, in FIG. 3, when the differentialamplification circuit is put in a state of balance, electromagnetchanges a condition in which electricity is turned on into a conditionin which electrically is cut off; whereas, in FIG. 5, electromagneticcoil 45 changes a condition in which electricity is cut off into acondition in which electricity is turned on.

FIG. 6 illustrates the third embodiment of the present invention, thatis, an embodiment whereby light receiving element 8 is so arranged thatit may rise and fall in front of the film.

When shutter button 29 is pressed down, release member 9 moves down viacoupling plate and its pin 9d engages with one arm of a retaining lever60 to rotate lever 60 counter-clockwise about an axle extending throughaxle hole 60a. Retaining lever 60 is biased clockwise and its arm 60bmoves into and out of engagement with one arm 61a of a three-armeddriving lever 61. Since driving lever 61 is biased clockwise by means ofa driving spring 61d, its second arm 61b rotates a mirror lever 62counter-clockwise via pin 62a, thereby effecting a counter-clockwiserotation of moving mirror 3 which is fixedly mounted on axle along withmirror lever 62. Also, during such counterclockwise rotation, arm end62b of mirror lever 62 closes switch 8,. At the same time, flange 61c ofdriving lever 61 engages with pin 63a of retaining lever 63 to rotate incounter-clockwise, so that arm end 6312 will be moved out of engagementwith projection 64b of working plate 64.

Working plate 64, which is guided during its movement right and left bymeans of guide grooves 64d, and which is urged toward the left by meansof a spring 65, has a toothed portion 64a along one edge. A gear 66 of agovernor engages with this toothed portion.

Accordingly, when arm end 63b and projection 64b are out of engagement,working plate 64 is driven to the left while being controlled by thegovernor, and diaphragm adjusting pin 16 of the attachable lens movestoward a flap 640 of plate 64 thereby reducing the aperture by means ofthe diaphragm blades (not shown in the drawing).

In this way the scene light which passed through the objective lens andthe diaphragm blades is brought incident upon light receiving element 8,and information on the brightness of the object and the diaphragmaperture is given to light receiving element 8.

The exposure controlling circuit is the same as that illustrated in FIG.5, in which, when the differential amplifier circuit is put in a stateof balance, electromagnetic coil 45, which is in a condition in whichelectricity is cut off, is fed with electric current, electromagnet 67is excited to attract armature 68a of stop lever 68 for turning itcounterclockwise, and hence retaining pawl 70 coupled with said stoplever 68 by coupling member 69 engages with ratched edge 66a of gear 66interlocking with gear 66 of the governor to retain its rotation and tostop the movement of working plate 64. At the I same time, hook portion68b of stop lever 68 and lever 71 are out of engagement.

A supporting frame 8a of light receiving element 8, is mounted onrotating axle 72 which is biased for movement in a direction by means ofa spring (not shown in the drawing). When axle 72 and frame 8a arerotated clockwise at the instant lever 71 and hook portion 68b are outof engagement, light receiving element 8 withdraws from itsphotographing optical path. At the same time, pin 73a, of levers 73which is fixedly mounted on revolving axle 72, engages with a projection74a of shutter release lever 74 to rotate projection 74acounter-clockwise. The other arm 74b therefore releases the retention ofcam 75 which is fixedly mounted on axle 40 along with front curtaintoothed wheel 41.

Hence, in the same manner as in the second example illustrated in FIG.4, front curtain 46 is driven via axle 40 and gears 41 and 42 to startexposure. After this, when the time of the shutter speed set up in thiscamera has passed, rear curtain is also driven, and exposure isterminated.

After exposure is terminated, the various elements.

may be returned to their positions as shown in FIG. 6 by rotatingdriving lever 61 counter-clockwise against its spring 61d and bringingits first arm 61a into engagement with hook portion a of retaining lever60.

It-will be understood by those skilled in the art that the embodimentsof the invention shown and described herein are subject to modificationwithout departing from the scope and spirit of the invention.

Accordingly, it should be understood that the invention is not limitedby the embodiments shown and dea diaphragm adjusting member interlockingwith said working member for opening the diaphragm aperture fully whensaid working member is in said charged position and for reducing downsaid diaphragm aperture with the displacement of said working member tosaid rest position;

stopper means engageable with said working member for stopping thedisplacement of thesame;

an exposure controlling circuit provided with a detecting circuitincluding said light receiving element and generatable output as afunction of light intensity incident on the light receiving element, thesensitivity of the film used and the set speed of said shutter; and

electromagnetic means responsive to the output of said exposurecontrolling circuit to actuate said stopper means, whereby saiddiaphragm aperture is stopped at a size according to said scene light.

2. A photographic camera as set forth in claim 1, fur ther comprising acamera body, including said working member and wherein said objectivelens is detachable and exhangeable and includes said diaphragm adjustingmember which is interlocked with said working member in said camera bodywhen said exchangeable objec tive lens is attached to said camera body.

3. A photographic camera as set forth in claim 1, wherein saidelectromagnetic means includes an electromagnet which is energized withthe generation of the output in said exposure controlling circuit.

4. A photographic camera as set forth in claim 1, wherein saidelectromagnetic means includes an electrom'agnet which is de-energizedwith the generation of the output in said exposure controlling circuit.

5. A photographic camera as set forth in claim 1, wherein said workingmember is provided with a toothed portion and said stopper means isprovided with a pawl engageable with said toothed portion of saidworking member.

6. A photographic camera as set forth in claim wherein the camera is asingle lens reflex camera hav ing a view finder and comprising:

a shutter having a front curtain movable from a cocked position to arest position for initiating exposure;

a rear curtain movable from a cocked position to a rest position forterminating said exposure;

a shutter speed setting means for controlling the time interval at whichsaid front curtain and said rear curtain is actuated to be driven;

a reflecting mirror fixedly mounted on an axle for movement between aviewing position for reflecting the scene light passed through the lensand the diaphragm aperture to the view finder and a picture-takingposition;

said light receiving element receiving said scene light being arrangedwithin an optical path of said scene light reflected by said reflectingmirror at the viewing position;

a camera body;

a switch of said controlling circuit being closed with the releaseoperation of said release member;

a retaining member for retaining said working member at its chargedposition thereof and for releasing said retention through said releaseoperation of said release member after the closing of said switch isterminated;

a locking member for retaining said retaining mem ber in its releasedposition and for moving said retaining member into and out of engagementwith said stopper means attracted to said electromagnetic means;

a camera release lever operatively mounted on said camera body foractuation by said release member;

a mirror lever rotatably mounted on said mirror axle for rotating saidmirror from the viewing position to the picture-taking position inrelationto the release working of said camera release lever actuatedduring the last stage of the stroke of said release member during saidsaid release operation;

a mirror return lever fixedly mounted on said mirror axle andcooperating with said mirror lever for returning said mirror from saidpicture-taking position to said viewing position;

a connecting lever operatively mounted on said camera body forengagement with said mirror return lever and said retaining member; and

means cooperating with said rear curtain for releasing the engagement ofsaid connecting lever with said mirror return lever in relation to thecompletion of the driving of said return lever from the cocked positionto the rest position.

7. A photographic camera as set forth in claim 6 wherein said connectinglever, when in engagement with said mirror return lever, engages withsaid retaining member which engages with said stopper means, said pawlof said stopper means engaging with said toothed portion of said workingmember thereby retaining said retaining member; and wherein saidconnecting member, when moved out of engagement with said mirror returnlever in relation with the completion of the rear curtain driving,rotates in the position where said stopper means is brought into contactwith said electromagnetic means, thereby breaking the engagement of saidlocking member with said retaining member.

8. An automatic exposure control device for a photographic camera havingan objective lens and a dia phragm, comprising:

a shutter having a front curtain movable from a cocked position to arest position for initiating exposure;

a rear curtain movable from a cocked position to a rest position forterminating said exposure;

a shutter speed setting member controlling the time interval at whichsaid front curtain and said rear curtain is actuated to be driven;

a light receiving element receiving a scene light passing through theobjective lens and an aperture of the diaphragm; I

a view finder;

a release member for initiating exposure operation of said shutter; I

a working member displaceable from its charged position to its positionof rest in relation to the operation of said release member;

a reflecting mirror fixedly mounted on an axle for movement between aviewing position for reflecting the scene light passed through theobjective lens and the diaphragm aperture to the view finder and apicture-taking position;

said light receiving element for receiving said scene light beingarranged within an optical path of said scene light reflected by saidreflecting mirror at the viewing position; I

said working member having a toothed portion and means biasing saidworking member for displacement while releasing the retention of saidretaining member;

stopper means provided with a pawl engageable with said toothed portionfor stopping the displacement of said work member;

an exposure controlling circuit provided with a de- 0 tecting circuitincluding said light receiving element and generatable output as afunction of light intensity incident on the light receiving element, thesensitivity of the film used and the set speed of said shutter; 15

electromagnetic means responsive to the output of said exposurecontrolling circuit. to actuate said stopper means, whereby saiddiaphragm aperture is stopped at a size according to said scene light;

said exposure controlling circuit including a switch which is closed ata first stage of a stroke of said release member during its releaseoperation;

a retaining member for retaining said working member at its chargedposition thereof and for releasing said retention through said releaseoperation of said release member at a second stage of its stroke;

a mirror lever mounted for rotation on said mirror axle and cooperatingwith said stopper means so as to be released thereby when said pawl ofsaid stopper means is brought into engagement with said toothed portionand thereby driving said movable reflecting mirror from said viewingposition to said picture-taking position;

a mirror return lever fixedly mounted on said mirror axle andcooperating with said mirror lever for re turning said mirror from saidpicture-taking position to said viewing position; and

a shutter release lever mounted for cooperation with said mirror leverfor releasing the driving of said front curtain from the cocked positionto the rest 40 position with the releasing of said mirror lever.

9. An automatic exposure control device for a photographic camera havingan objective lens and diaphragm, comprising:

a camera body;

a curtain shutter having a front curtain movable from a cocked positionto a rest position for initiating exposure, a rear curtain movable froma cocked position to a rest position for terminating said exposure;

a light receiving element receiving a scene light passing through theobjective lens and an aperture of the diaphragm;

a view finder;

a shutter speed setting member for controlling the time interval atwhich said front curtain and said rear curtain is actuated to be driven;

a reflecting mirror fixedly mounted on an axle for movement between aviewing position for reflecting the scene light passed through theobjective lens and the diaphragm aperture to the view finder and thepicture-taking position for passing said scene light toward a film;

said light receiving element being positioned between said reflectingmirror and said shutter curtains and movable between a first positionwithin the optical path of the scene light when said reflecting mirroris in said picture-taking position for receiving said scene light and asecond position withdrawn from said optical path;

a release member for initiating exposure operation of said curtainshutter;

a driving member operatively mounted on said camera body and beingretained by said release member to be released during the releaseoperation of said release member;

a mirror lever fixedly mounted on said mirror axle and engaging withsaid driving member;

a working member provided with a toothed portion and being urged by aspring means to be driven from a charged position to a rest position;

a retaining member operatively mounted on said camera body and beingengageable with said driving member for retaining said working member atsaid charged position thereof against said spring means;

governor means operatively mounted on said camera body and beingprovided with a gear for engaging with said toothed portion;

a diaphragm adjusting member interlocking with said working member foropening the diaphragm aperture fully when said working member isretained at the charged position and for cutting down said diaphragmaperture with the displacement of said working member from its chargedposition to its rest position;

stopper means provided with a pawl engageable with said governor meansfor stopping the displacement of said working member;

an exposure controlling circuit provided with a detecting circuitincluding said light receiving element and generatable output as afunction of light intensity incident on the light receiving element, thesensitivity of the film used and the set speed of said shutter;

electromagnetic means responsive to the output of said exposurecontrolling circuit to actuate said stopper means, whereby saiddiaphragm aperture is stopped at a size according to said scene light;and

means on said light receiving element engaging with said stopper meansfor driving said light receiving element from the first position to thesecond position with the actuation of said stopper means. =1 l=

1. An automatic exposure control device for a photographic camera having an objective lens and a diaphragm, comprising: a light receiving element receiving scene light passing through the objective lens and an aperture of the diaphragm; a shutter for giving exposure according to set shutter speeds; a release member for initiating exposure operation of said shutter; a working member displaceable from its charged position to its position of rest in relation to the operation of said release member; a diaphragm adjusting member interlocking with said working member for opening the diaphragm aperture fully when said working member is in said charged position and for reducing down said diaphragm aperture with the displacement of said working member to said rest position; stopper means engageable with said working member for stopping the displacement of the same; an exposure controlling circuit provided with a detecting circuit including said light receiving element and generatable output as a function of light intensity incident on the light receiving element, the sensitivity of the film used and the set speed of said shutter; and electromagnetic means responsive to the output of said exposure controlling circuit to actuate said stopper means, whereby said diaphragm aperture is stopped at a size according to said scene light.
 2. A photographic camera as set forth in claim 1, further comprising a camera body, including said working member and wherein said objective lens is detachable and exhangeable and includes said diaphragm adjusting member which is interlocked with said working member in said camera body when said exchangeable objective lens is attached to said camera body.
 3. A photographic camera as set forth in claim 1, wherein said electromagnetic means includes an electromagnet which is energized with the generation of the output in said exposure controlling circuit.
 4. A photographic camera as set forth in claim 1, wherein said electromagnetic means includes an electromagnet which is de-energized with the generation of the output in said exposure controlling circuit.
 5. A photographic camera as set forth in claim 1, wherein said working member is provided with a toothed portion and said stopper means is provided with a pawl engageable with said toothed portion of said working member.
 6. A photographic camera as set forth in claim 5 wherein the camera is a single lens reflex camera having a view finder and comprising: a shutter having a front curtain movable from a cocked position to a rest position for initiating exposure; a rear curtain movable from a cocked position to a rest position for terminating said exposure; a shutter speed setting means for controlling the time interval at which said front curtain and said rear curtain is actuated to be driven; a reflecting mirror fixedly mounted on an axle for movement between a viewing position for reflecting the scene light passed through the lens and the diaphragm aperture to the view finder and a picture-taking position; said light receiving element receiving said scene light being arranged within an optical path of said scene light reflected by said reflecting mirror at the viewing position; a camera body; a switch of said controlling circuit being closed with the release operation of said release member; a retaining member for retaining said working member at its charged position thereof and for releasing said retention through said release operation of said release member after the closing of said switch is terminated; a locking member for retaining said retaining member in its released position and for moving said retaining member into and out of engagement with said stopper means attracted to said electromagnetic means; a camera release lever operatively mounted on said camera body for actuation by said release member; a mirror lever rotatably mounted on said mirror axle for rotating said mirror from the viewing position to the picture-taking position in relation to the release working of said camera release lever actuated during the last stage of the stroke of said release member during said said release operation; a mirror return lever fixedly mounted on said mirror axle and cooperating with said mirror lever for returning said mirror from said picture-taking position to said viewing position; a connecting lever operatively mounted on said camera body for engagement with said mirror return lever and said retaining member; and means cooperating with said rear curtain for releasing the engagement of said connecting lever with said mirror return lever in relation to the completion of the driving of said return lever from the cocked position to the rest position.
 7. A photographic camera as set forth in claim 6 wherein said connecting lever, when in engagement with said mirror return lever, engages with said retaining member which engages with said stopper means, said pawl of said stopper means engaging with said toothed portion of said working member thereby retaining said retaining member; and wherein said connecting member, when moved out of engagement with said mirror return lever in relation with the completion of the rear curtain driving, rotates in the position where said stopper means is brought into contact with said electromagnetic means, thereby breaking the engagement of said locking member with said retaining member.
 8. An automatic exposure control device for a photographic camera having an objective lens and a diaphragm, comprising: a shutter having a front curtain movable from a cocked position to a rest position for initiating exposure; a rear curtain movable from a cocked position to a rest position for terminating said exposure; a shutter speed setting member controlling the time interval at which said front curtain and said rear curtain is actuated to be driven; a light receiving element receiving a scene light passing through the objective lens and an aperture of the diaphragm; a view finder; a release member for initiating exposure operation of said shutter; a working member displaceable from its charged position to its position of rest in relation to the operation of said release member; a reflecting mirror fixedly mounted on an axle for movement between a viewing position for reflecting the scene light passed through the objective lens and the diaphragm aperture to the view finder and a picture-taking position; said light receiving element for receiving said scene light being arranged within an optical path of said scene light reflected by said reflecting mirror at the viewing position; said working member having a toothed portion and means biasing said working member for displacement while releasing the retention of said retaining member; stopper means provided with a pawl engageable with said toothed portion for stopping the displacement of said work member; an exposure controlling circuit provided with a detecting circuit including said light receiving element and generatable output as a function of light intensity incident on the light receiving element, the sensitivity of the film used and the set speed of said shutter; electromagnetic means responsive to the output of said exposure controlling circuit to actuate said stopper means, whereby said diaphragm aperture is stopped at a size according to said scene light; said exposure controlling circuIt including a switch which is closed at a first stage of a stroke of said release member during its release operation; a retaining member for retaining said working member at its charged position thereof and for releasing said retention through said release operation of said release member at a second stage of its stroke; a mirror lever mounted for rotation on said mirror axle and cooperating with said stopper means so as to be released thereby when said pawl of said stopper means is brought into engagement with said toothed portion and thereby driving said movable reflecting mirror from said viewing position to said picture-taking position; a mirror return lever fixedly mounted on said mirror axle and cooperating with said mirror lever for returning said mirror from said picture-taking position to said viewing position; and a shutter release lever mounted for cooperation with said mirror lever for releasing the driving of said front curtain from the cocked position to the rest position with the releasing of said mirror lever.
 9. An automatic exposure control device for a photographic camera having an objective lens and diaphragm, comprising: a camera body; a curtain shutter having a front curtain movable from a cocked position to a rest position for initiating exposure, a rear curtain movable from a cocked position to a rest position for terminating said exposure; a light receiving element receiving a scene light passing through the objective lens and an aperture of the diaphragm; a view finder; a shutter speed setting member for controlling the time interval at which said front curtain and said rear curtain is actuated to be driven; a reflecting mirror fixedly mounted on an axle for movement between a viewing position for reflecting the scene light passed through the objective lens and the diaphragm aperture to the view finder and the picture-taking position for passing said scene light toward a film; said light receiving element being positioned between said reflecting mirror and said shutter curtains and movable between a first position within the optical path of the scene light when said reflecting mirror is in said picture-taking position for receiving said scene light and a second position withdrawn from said optical path; a release member for initiating exposure operation of said curtain shutter; a driving member operatively mounted on said camera body and being retained by said release member to be released during the release operation of said release member; a mirror lever fixedly mounted on said mirror axle and engaging with said driving member; a working member provided with a toothed portion and being urged by a spring means to be driven from a charged position to a rest position; a retaining member operatively mounted on said camera body and being engageable with said driving member for retaining said working member at said charged position thereof against said spring means; governor means operatively mounted on said camera body and being provided with a gear for engaging with said toothed portion; a diaphragm adjusting member interlocking with said working member for opening the diaphragm aperture fully when said working member is retained at the charged position and for cutting down said diaphragm aperture with the displacement of said working member from its charged position to its rest position; stopper means provided with a pawl engageable with said governor means for stopping the displacement of said working member; an exposure controlling circuit provided with a detecting circuit including said light receiving element and generatable output as a function of light intensity incident on the light receiving element, the sensitivity of the film used and the set speed of said shutter; electromagnetic means responsive to the output of said exposure controlling circuit to actuate said stopper means, whereby said diaphragm aperture is stopped at a size acCording to said scene light; and means on said light receiving element engaging with said stopper means for driving said light receiving element from the first position to the second position with the actuation of said stopper means. 